1. Technical Field
The present disclosure relates to an LED lamp incorporating an LED chip serving as a light source.
2. Related Art
Demand for LED lamps or LED light bulbs has recently been increasing as substitute for incandescent lamps having higher electrical power consumption. The LED lamps have far less power consumption. One type of LED lamp includes a metal heat dissipator made of a metal, such as aluminum, having high heat conductivity, a socket mounted on one end of the heat dissipator, a glove comprising a light-transmissive glass or plastic material having a semi-spherical top and attached to the other end of the heat dissipator, a module substrate on which an LED chip is mounted and a lighting circuit supplying electrical power to the LED chip. The module substrate and the lighting circuit are mounted on the heat dissipator, and the LED chip is covered by the glove. The lighting circuit and the socket are electrically connected to each other. This type of LED lamp is disclosed by Japanese Patent Application Publication Nos. JP-A-2011-70972, JP-A-2011-82132, JP-A-2011-90828 and JP-A-2011-91033.
Light emitted by a filament serving as a light source for an incandescent lamp is diffused around thereby to evenly illuminate the surrounding area. On the other hand, light emitted by the LED chip used as a light source for an LED lamp has a high directionality and accordingly has a characteristic of illuminating a frontward narrow region by intense light.
Furthermore, the temperature of the filament of the incandescent lamp sometimes rises up to 2,000° C. during turn-on. As a result, the surface of the glove covering the filament is heated thereby to have a high temperature such that touch or contact to the glove surface would result in burn injury.
On the other hand, the LED chip serving as the light source for the LED lamp has an exceedingly lower calorific value during turn-on as compared with the filament. Accordingly, even the temperature of the heat dissipator rises to about several dozen degrees at the highest during turn-on. The glove has such a characteristic that the temperature thereof is so low that the glove can be touched during turn-on as compared with the incandescent lamp.